This invention relates generally to mirrors for vehicles and, more particularly, to mirrors that are capable of dimming in response to a high intensity incidence light.
Vehicles generally include an interior rearview mirror and two side exterior rearview mirrors. During nighttime driving conditions, a persistent problem for the driver has been glare caused by the reflection of following vehicle headlights in these rearview mirrors. Thus, there is a need to reduce this glare while permitting the driver to see behind the vehicle.
Prior art solutions to nighttime headlight glare have included manual manipulation of the interior rearview mirror and electronic dimming of the rearview mirrors. In the prior art, electronic dimming of the rearview mirrors has comprised the use of electrochromic films or gels that alter their transmissivity based on electrochromic effects in liquid crystals. These electronic systems modify the state of charge in an electric field surrounding the liquid crystals in the film or gel on the mirror. The net result of a modification in the state of charge is a change in the reflectivity of the mirror.
One disadvantage with prior electronic dimming methods has been the cost. In addition, these prior art electronic systems generally respond slowly to the glare from following vehicle headlights.
Thus, it is desirable to provide a low cost electronic dimming mechanism for rearview mirrors. It is furthermore desirable to provide such an electronic dimming mechanism that responds more rapidly to the presence of following vehicle headlights at nighttime.